Airplane



' or air foils.

ATENT OFFICE GLENN A. BERRY, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO BERRY AIRCRAFT, LTD., OF SAN FRANCISCO, CALIFORNIA, A CORPORATION OF CALIFORNIA AIRPLANE Application filed August 21, 1929. Serial No. 387,355.

This invention relates to airplanes, and especially to a novel mounting and position- 'ing of a plurality of superposed air foils with relation to the slip stream of the propellcr.

The object of the present invention is to generally improve the construction and operation of airplanes; by utilizing to the greatest advantage the propeller thrust, that is, the air or slip stream projected rearwardly under high velocity by the propeller.

In the present instance I accomplish this by providing a propeller having a diameter substantially equal to the span of the wings I may prefer to provide tandem propellers, one forward of the other and driven in opposite directions so as to smooth out and remove any rotation or twist in. the slip stream. The propeller cooperates with a plurality of superposed interspaced air foils of long span and small chord with which means are associated for tilting or varying the angle of incidence of the air foils so as to deflect the slip stream of the propellers downwardly, thereby obtaining a lift sufficient to insure a quick take-off and also permitting slow landing speeds.

The airplane is shown by way of example in the accompanying drawings, in which:

Fig. 1 is a side elevation of the plane,

Fig. 2 is a front View of the same,

Fig. 3 is a central longitudinal vertical section, showing a differential gear mechanism whereby the propellers are driven in opposite directions, and whereby they may be rotated at varying'speeds.

Referring to the drawings in detail, and particularly Figs. 1 and 2, A indicates the fuselage of a plane, 2 the running gear, 3 the rudder, 4 the engine, 5 and 6 the propellers, and 8 the wings or air foils. The engine is, in this instance, disposedabove the fuselage, and is sup-ported on a frame generally indicated at 9. Pivotally mounted on this frame,

as at 10, 10 is a frame consisting of uprights 11, 11a, 11b and 11a, said uprights being connected by the air foils 8.

The' upper air 'foils extend completely across the uprights 11 to 110 inclusive, while the lower air foils are disposed on each side of the frame 9 and the fuselagethat is, the air foils indicated at 8a extend from the uprights 11a to the uprights 11, while the air foils indicated at 87) extend from the uprights 11?) to the uprights 110. This straddling arrangement is important as it permits the air foil frame to pivot on the axis 10 so that the angle of incidence of the air foils maybe changed, as will hereinafter bedescribed.

The air foils employed are arranged in a manner similar toa Venetian blind (see Fig. 2). Each air foil presents a comparatively long span and a small chord. The area covered by the air foils is, in this instance, slightly greater than the area swept by the propellers. This is also important, as one of the features of the present invention is that of utilizing as much as possible the lifting force of the slip stream of the propellers.

T hat is, the stream of air which is projected rearwardly by the propellers under high velocity. It is for this reason desirable to position the planes as closely behind the propellers as possible.

The slip stream of an ordinary propeller has a constant twist or swirl, and such a slip stream would have. comparatively little efficiency as far as lifting effect is concerned. In as much as the propeller has a large diameter, the ailerons would come partially within the slip stream and obtain lateral balance at high incidence and low speeds thus enabling the ship to make a stalled landing under power.

In the present instance the slip stream is smoothed out and the twist in the stream is entirely eliminated. This is accomplished by using tandem propellers, one forwardly of the other, as indicated at 5 and 6. These propellers are driven in opposite directions, and as such smooth out the slip stream and eliminate the twist. Hence the full lifting effect of the slip stream may be obtained when the air foils are balanced or placed rearwardly thereof. However I may desire to utilize but one propeller.

By the arrangement of the plane as here shown, it is possible'to use propellers of large diameter which operate at comparatively slow speeds, and a double lifting effect is obtained, first that of the slip stream, and secondly that of the forward momentum of the plane as a whole.

The driving mechanism whereby rotary motion is transmitted to the propellers in an opposite direction, is shown in Fig. 3, in which A indicates the propeller or drive shaft. Keyed to this shaft is a gear B, and meshing with said gear is a gear C. Gears C, D and F are keyed together, or formed integral with relation to each other but they are free to revolve on the shaft end.

Gear E is keyed to the tubular shaft indicated at J, and it meshes with gear D. The gear indicated at H is keyed to a tubular shaft I, and meshes with the gear F through an idler gear G. The tubular shafts J and I are free to rotate with relation to each other and are supported in the bearing K which may form a part of the gear case housing- If shaft A, together with the gear B revolves in a clockwise direction, the same direction of rotation will be transmitted to the tubular shaft J. But if gear H is driven through the idler gear G, tubular shaft I will rotate in the opposite direction.

The propeller 6 is secured on the shaft I and the propeller 5 on the shaft J. Hence, the propellers will rotate in opposite directions. It should also be noted that the propellers may be rotated at different speeds, as the gear casing or housing is free to rotate about the shafts A and I.

The diflerential gear drive illustrated forms the subject matter of a co-pending application and for that reason forms no part of the subject matter of the present claims. It is, however, essential that some mechanism be disclosed for driving the propellers in opposite directions. It is for this reason that the differential gear drive has been illustrated.

By referring to Fig. 1 it will be noted that means are provided for adjusting the angle of the air foil frame, the means illustrated being a hand operated lever 15, a rocker arm 16, a link 17 and a link 18, the link 18 being connected to the lever 15. The lever may be locked with relation to a ratchet 19. By swinging thelever inone direction the air foil frame will swing about'its pivotal axis 10 and will assume either a vertical or a rearwardly tilted position. Converse-1y, by

swinging lever 15 in the opposite direction the air foil frame will assume a vertical or forwardly tilted position. In this manner it is possible to change the angle of incidence of the air foils with relation to the slip stream of the propellers.

It will be understood that the airplane will be equipped with the usual ailerons or other means for laterally balancing the same. For instance, it is possible to provide a section of the air foils with movable wing tips, or by having the bottom wings, indicated at 20, pivotally supported with relation to the fuselage so that they may be controlled in the usual manner. The other controls, such as rudders, etc., will be connected and operated in the usual manner.

In actual practice it will be understood that usually airplanes must attain a considerably forward momentum before any lift whatsoever is created. This forward speed is obtained and maintained by the propeller thrust. The airplane must be propelled by this thrust to a point where the air speed is sufficient to lift the ship by the rarefication of the air over the wings, and by reaction underneath the wings. For constructional reasons the average airplane has a small propeller and very wide wings in relation to their span. The result of this is a tremendous waste of power, due to the great speed necessary for flight.

In practice it has been found that the leading edge of a plane or air foil is by far the most efficient. In fact, the first quarter of the chord provides as much lift as the rear three-fourths. Much of the lift of thetrailing edge is made negative by the increased skin friction.

In nature, the birds with the greatest span in relation to their chord, are the best soarers. This is due to the fact that air having small weight, the small enertia expended is soon spent. The best of soarers, such as the albatross, has a span chord relation of one to fourteen.

Because small propellers are generally used, it is necessary to run them at high velocity. The thrust of a propeller increases as the square of the velocity, and the power necessary as the cube of the Velocity. In view of these facts, it naturally follows that the more air engaged at lower velocity, the greater economy of power.

In order to make it possible for a plane to take off at slow speed, it occurred to me that it would be necessary to approximate natures scheme of actively engaging all the air the ship comes in contact with. A flapping bird. in taking off, propels the air downwardly and backward. The ordinary airplane shoots the air backwards by means of its propellers, but it does not raise off the ground until it has gained suflicient momentum to cause such rarefication above the wings and reaction beneath the wings as will lift the same.

In the present instance I have taken advantage of the high velocity air orslip stream projected rearwardly by the propellers, and I have provided means whereby the angle of incidence of the air foils can be so changed as to deflect the air stream downwardly and thereby materially aid in lifting the ship so as to make it possible to obtain a quick takeoff. Knowing that the slip stream of a propeller has a rotary or corkscrew movement,

I found that this could be corrected or counteracted by using two propellers driven in opposite directions. Hence I have produced a smooth, straight slip stream which can be utilized to full advantage when air foilsof long span and small chord are placed directly rearwardly thereof.

The narrow superimposed wings have, in actual test, proven that it is possible to make a steep, slow glide when landing. This is due to the fact that air has such a short distance to travel that it does not burble and seems to be sucked through the structure in an even flow. With the steep slow glide, and at the moment of landing to increase the incidence makes for almost a vertical landing and no run. In addition, because of the narrowness of the wings, they show no tendency to stall and side slip. The rear of the plane is held up by the tail area, and in view thereof the front drops immediately to a gliding angle at a speed less than flying speed, therefore producing a plane which is stall-proof.

Because of the changeable incidence the ship is at all times level longitudinally and therefore will show no tendency to nose dive.

IVhile the features of the invention are more or less specifically described, I wish it understood that various changes may be resorted to within the scope of the appended claims, for example, sets of air foils in tandem may be used and propeller may be driven in opposite directions by simple bevel gears or chains, the propellers may or may not be variable pitch and a single propeller may be used by removing the air foils on the sector of the propeller where the rotation of the slip stream has a downward trend, or by having the airfoils in the aforesaid downward sector adjustable to a neutral angle of incidence. This arrangement while not so efficient as a double propeller is nevertheless simpler.

In facing a propeller rotating clockwise, the stream has a down and backward trend in the righthand quarter, a left to right and backward trend in the top quarter and a right to left and backward trend in the bottom quarter; top and bottom and left quarters meeting a set of superimposed air foils arranged as shown in the drawings would be deflected downward, thus creating lift. The air in the righthandquarter has already a downward direction and also creates lift. Also other methods of changing the incidence may be resorted to. For instance, each air foil may rotateon its own axis instead of a group axis.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1. In adevice of the character described a tandem propeller adapted to project a nonrotating slip stream, and a purality of superposed interspaced air foils closely disposed 2. In a device of the character described a tandem propeller disposed to project a nonrotating slip stream, a plurality of super posed interspaced air foils disposed adjacent the propeller directly in the path of the slip stream, and covering an area substantially the same as the area of the slip stream.

3. An airplane including a fuselage, a tan dem propeller disposed at the front thereof, and adapted to be driven to project a nonrotating slip stream, a plurality of superposed interspaced air foils disposed adjacent the propeller laterally ofthe fuselage and directly in the path of the slip stream, said air foils presenting a long span and a small chord, and covering an area slightly greater than the area of the slip stream.

4. In a device of the character described tandem propellers, of opposite pitch one propeller being driven in a direction opposite to the other, and a plurality of superposed interspaced air foils disposed in the slipstream of the propellers, said air foils having a span slightly greater than the blast area swept by the propellers, and the total height of the superposed air foils being also slightly greater than the area swept by the propellers.

5. In a device of the character described tandem propellers, of opposite pitch one p ropeller being driven in a direction opposite to the other, a plurality of superposed inter spaced air foils disposed in the slip stream of the propellers, said air foils having a span slightly greater than the area swept by the propellers, and the total height of the superposed air foils being also slightly greater than the blast area swept by thepropellers, said air foils presenting a chord which is small compared to the span.

6. In an airplane of the character described a fuselage, a motor supported thereby, a pair of propellers of opposite pitch disposed one forwardly of the other, means connected with the engine whereby the propellers are driven in opposite directions, a frame pivotally supported with relation to the fuselage. and a plurality of intersnaced superposed air foils supported by the frame and disposed in the slip stream of the propellers.

7. In an airplane of the character described a fuselage, a motor supported thereby, a pair of propellers disposed one forwardly of the other, means connected with the engine whereby the propellers may be driven in opposite directions, a frame pivotally supported with relation to the fuselage, a plurality of interspaced superposed air foils supported by the frame and disposed in the slip stream of the propellers, and means swinging the frame about its pivotal support and for securing it when swung so as to vary the angle of incidence of the air foils.

8. In a device of the character described, a tandem propeller disposed to project a nonrotating sli stream, a plurality of superposed interspace air foils disposed adjacent the propeller directly in the path of the slip stream and covering an area substantially the same as the area of the slip stream, and means for Varying the angle of incidence of the air foils with relation to the slip stream.

GLENN A. BERRY. 

